It is known in convention sorting apparatuses to place the packages to be sorted one after another on consecutive trays mounted on a conveyor and to remove the packages by tilting the trays at their respective sorting positions, thereby causing the packages to slide downward and off the trays.
However, these sorting apparatus are likely to be restricted by the shape of packages, and are therefore often not suitable for sorting many kinds of packages. A further known disadvantage of previously known tray-tilting type sorting apparatus is that they are arranged such that each tray is maintained horizontally during the conveyance of the package and tilted at a predetermined position transversely with respect to the conveyance direction, so that the package must be slid obliquely downward because the tray continues to be moved during such tilt operation. Since the sliding time period and the sliding length required for sliding the package along the tray is dependent on the weight of the package, it is necessary to provide a large area enough to receive the package. If a large receiving area is not provided, the package is likely to be conveyed to a next package receiving area, etc. until the package is completely slid downward and off the tray. The higher the speed of the tray movement, the higher the frequency of this problem. Additionally, since in conventional tray-type sorter the package is slid by its own weight when the latch is released, the sliding speed of the package cannot be controlled, so that some packages may be damaged.
In order to solve the problems noted above, U.S. Pat. No. 4,744,454 discloses a conveyor element in which a tray carrying a package thereon is capable of being tilted obliquely forward. The disclosed conveyor element, however, must have a plurality of bearings and a plurality of shafts for orientation, as well as a universal joint and a spring, and furthermore it is required to provide additionally a lever and a lock mechanism for tilting the tray at a sliding-down position. Further, since the lever is moved three-dimensionally when the tray is tilted, the lever and the tilting switch must be extremely complicated in construction. The entire arrangement of the U.S. Pat. No. 4,744,454 device is therefore quite complicated. As a result, the number of component parts and the assembling work therefor, and the associated increase in cost and maintenance work are undesirable.